Synthesis of organic phosphonic acid small molecule material for hole transport and application of organic phosphonic acid small molecule material in perovskite solar cell

Abstract

The invention belongs to the technical field of solar cells, and relates to synthesis of an organic phosphonic acid micromolecule material for hole transport and application of the organic phosphonic acid micromolecule material in perovskite solar cells, the micromolecule material adopts iminodibenzyl as a central core, an n-butyl alkyl chain as a connecting part, and a phosphate group as an end group; through a more sufficient electron delocalization space, coordination with perovskite is enhanced, hole transport capability is improved, surface defects of perovskite are effectively passivated, and charge transport capability with an ITO substrate is enhanced. The preparation method of the phosphonic acid small-molecule material is simple and reliable, can be used for preparing an efficient perovskite solar cell at low cost, and has wide application prospects and market potential.

Description

Technical field:

[0001] The present invention belongs to the technical field of solar cell materials, and specifically relates to the synthesis of an organic phosphonic acid small molecule material for hole transport and its application in perovskite solar cells. The organic phosphonic acid small molecule is designed to use iminodibenzyl as a central core, an n-butyl alkyl chain as a connecting part, and a phosphate group as an end group, and is used as a hole transport layer material in an inverse perovskite solar cell. Background technology:

[0002] Perovskite solar cells (PSCs), as the third-generation solar cell technology, are gradually becoming the focus in the field of solar cells due to their high energy conversion efficiency, low cost and environmental protection characteristics.

[0003] Inverse perovskite solar cells are receiving extensive attention from academia and industry due to their advantages such as high stability, high efficiency, low cost, low-temperature processing, and compatibility with stacked cell structures. Inverse perovskite solar cells have the advantages of low hysteresis effect, low-temperature preparation, and long-term working stability, which are conducive to large-scale industrial production.

[0004] Traditional inverse perovskite solar cells mainly use poly (3,4-ethylenedioxythiophene): polystyrene sulfonate) (PEDOT:PSS) and nickel oxide (NiOx) as hole transport layer (HTL) materials. PEDOT:PSS has the advantages of excellent conductivity, high transmittance, good energy level matching with perovskite materials, and compatibility with low-temperature annealing process and flexible photovoltaic devices. However, it also has problems such as low interface hole separation and transmission rate, acid corrosion, and easy dissolution by perovskite precursor solution. NiOx has a stable crystal structure and non-corrosiveness, which makes the corresponding PSCs have high light and thermal stability. At the same time, nickel oxide also has good high hole mobility and good hole extraction ability. However, due to the large band gap of nickel oxide, the Fermi level of NiOx and the perovskite absorption layer does not match, resulting in a relatively large energy level offset between the interfaces after contact and a weak built-in electric field. In addition, NiOx films prepared at low temperatures are prone to some defects, which increase the chance of carrier recombination and thus reduce the hole collection efficiency. Summary of the invention:

[0005] In view of the shortcomings of the traditional hole transport layer of perovskite solar cells, the present invention provides an organic phosphonic acid small molecule material (YG32) as a hole transport layer. The small molecule has a suitable energy level and functional group to improve the efficiency and stability of perovskite solar cells. Its molecular structure is as follows:

[0006]

[0007] The aromatic phosphonic acid small molecule material involved in the present invention is designed to use iminodibenzyl as a central core, an n-butyl alkyl chain as a connecting part, and a phosphoric acid group as an end group.

[0008] The present invention also provides a method for preparing the organic phosphonic acid small molecule material, and the specific steps are as follows:

[0009] (1) Adding iminodibenzyl, 0.66 g of tetrabutylbromosilane, 1,4-dibromobutane, sodium hydroxide and ultrapure water into a single-mouth bottle; evacuating the bottle, filling it with nitrogen, and repeating the evacuation and degassing three times; heating the bottle to 50-90° C. to react; after the reaction, removing the excess tetrabutylbromosilane by extraction; and purifying the bottle by silica gel column chromatography (dichloromethane: petroleum ether = 1:4) to obtain a white solid, which is 5-(4-bromobutyl)-10,11-dihydro-5H-dibenzo[b,f]naphthalenepyridine;

[0010] (2) Add 5-(4-bromobutyl)-10,11-dihydro-5H-dibenzo[b,f]naphthalene and triethyl phosphite into a single-mouth bottle; evacuate, fill with nitrogen, and repeat the evacuation and degassing three times; heat to 120-180°C for reaction; after the reaction, remove the excess triethyl phosphite by vacuum distillation; then purify by silica gel column chromatography (dichloromethane:methanol=100:1) to obtain a colorless liquid, which is diethyl (4-(10,11-dihydro-5H-dibenzo[b,f]naphthalene-5-yl)butyl) phosphate;

[0011] (3) Diethyl (4-(10,11-dihydro-5H-dibenzo[b,f]azanaphthalen-5-yl)butyl) phosphate, trimethylsilane bromide and 1,4-dioxane are placed in a single-mouth bottle; vacuum is applied, nitrogen is introduced, and the gas is pumped and released three times; methanol is added to quench, and ultrapure water is added for hydrolysis, and the mixture is stirred; finally, a white powder is obtained by filtration, which is (4-(10,11-dihydro-5H-dibenzo[b,f]azanaphthalen-5-yl)butyl) phosphoric acid, i.e., an organic phosphonic acid small molecule material.

[0012] The present invention also provides the use of the organic phosphonic acid small molecule material as a hole transport layer in a perovskite solar cell device.

[0013] The present invention also provides a perovskite solar cell, which comprises a transparent conductive glass, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode which are stacked, and the hole transport layer is the organic phosphonic acid small molecule material.

[0014] The present invention also provides a photovoltaic cell, comprising the perovskite solar cell.

[0015] The design ideas and advantages of the present invention are:

[0016] 1. Structurally, the novel phosphonic acid small molecule prepared by the present invention has: (1) an iminodibenzyl group as the central core, which has greater electron delocalization than the common carbazole group central core, and thus has a more obvious stability improvement for the electron-rich conjugated central core containing ammonia, and is also beneficial for regulating the molecular energy level; (2) a coordinated n-butyl alkyl chain as a connecting part provides more configuration adjustment space for the molecular self-assembly process, which is beneficial for better adaptation of the molecule to the perovskite and more dense film formation, thereby improving the overall device performance; (3) a phosphate group as the end group, which is more tightly connected to ITO, and is beneficial for hole extraction.

[0017] 2. The heteroatom phosphonic acid small molecule material of the present invention has a wide band gap, good film-forming properties, low synthesis cost, mild preparation conditions, and a simple synthesis route, thereby reducing the cost of optimizing perovskite devices.

[0018] 3. The material prepared by the present invention, as a hole transport material, provides great help to the efficiency of perovskite solar cells. Good device performance is obtained, and the service life of perovskite solar cells under high temperature and light conditions is extended; its photoelectric conversion efficiency exceeds 24%, which is expected to be conducive to commercial development.

[0019] In summary, the present invention proposes an effective conjugated modification strategy to design a new type of phosphonic acid small molecule, which not only strengthens the coordination with perovskite and improves the hole transport capacity through more sufficient electron delocalization space, but also effectively passivates the surface defects of perovskite and enhances the charge transport capacity with the ITO substrate. The preparation method of the phosphonic acid small molecule material is simple and reliable, and can prepare efficient perovskite solar cells at low cost, with broad application prospects and market potential. Description of the drawings:

[0020] Figure 1 The synthetic route of the heteroatom phosphonic acid material YG32 prepared in Example 1

[0021] Figure 2 The heteroatom phosphonic acid material YG32 prepared in Example 1 1 H NMR

[0022] Figure 3 JV diagram of the perovskite solar cell based on the hybrid YG32 phosphonic acid material of the present invention Specific implementation method:

[0023] The technical solution of the present invention is further described below through specific embodiments in conjunction with the accompanying drawings.

[0024] Embodiment 1:

[0025] This embodiment relates to a method for preparing an organic phosphonic acid small molecule material for hole transport, specifically a method for preparing a conjugated phosphonic acid small molecule material (4-(10,11-dihydro-5H-dibenzo[b,f]azanaphthalen-5-yl)butyl)phosphoric acid (YG32), comprising the following three steps:

[0026] (1) 1 g of iminodibenzyl was placed in a 250 mL single-mouth bottle, and then 0.66 g of tetrabutylsilane bromide (TBAB), 15 mL of 1,4-dibromobutane, 1.024 g of sodium hydroxide (NaOH) and 2 mL of ultrapure water were added; the mixture was evacuated, filled with nitrogen, and the evacuation and degassing were repeated three times; the temperature was raised to 70°C and the reaction was continued for 24 hours; after the reaction was completed, the excess tetrabutylsilane bromide was removed by extraction; and then the mixture was purified by silica gel column chromatography (dichloromethane: petroleum ether = 1:4) to obtain 0.83 g of a white solid, which was 5-(4-bromobutyl)-10,11-dihydro-5H-dibenzo[b,f]naphthalenepyridine;

[0027]

[0028] (2) 0.83 g of 5-(4-bromobutyl)-10,11-dihydro-5H-dibenzo[b,f]naphthaleneazine was placed in a 250 mL single-mouth bottle, and 15 mL of triethyl phosphite was added; vacuum was evacuated, nitrogen was filled in, and the evacuation and degassing were repeated three times; the temperature was raised to 150° C. and reacted for 24 h; after the reaction was completed, the excess triethyl phosphite was removed by vacuum distillation at 150° C.; then, silica gel column chromatography (dichloromethane: methanol = 100:1) was used for purification to obtain 0.65 g of colorless liquid, which was diethyl (4-(10,11-dihydro-5H-dibenzo[b,f]naphthaleneazine-5-yl)butyl) phosphate;

[0029]

[0030] (3) 0.65 g of diethyl (4-(10,11-dihydro-5H-dibenzo[b,f]azanaphthalen-5-yl)butyl) phosphate was placed in a 250 mL single-mouth bottle, and 5 mL of trimethylsilane bromide and 20 mL of 1,4-dioxane were added; the reaction was evacuated, filled with nitrogen, and the evacuation and degassing were repeated three times; 10 mL of methanol was added to quench the reaction, and after stirring for 2 h, 50 mL of ultrapure water was added for hydrolysis, and stirred for 1 h; finally, 630 mg of white powder was obtained by filtration, and the white powder was confirmed to be (4-(10,11-dihydro-5H-dibenzo[b,f]azanaphthalen-5-yl)butyl)phosphoric acid (denoted as YG32) by hydrogen nuclear magnetic resonance spectroscopy.

[0031]

[0032] The final product YG32 1The results of H NMR characterization are as follows Figure 2 shown.

[0033] Embodiment 2:

[0034] This embodiment relates to the preparation of a perovskite solar cell device based on YG32 synthesized in Example 1 and the testing of its photovoltaic performance.

[0035] The prepared perovskite solar cell device is a pin system, which has five parts, namely, a transparent conductive glass substrate (ITO) covered with indium tin oxide, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode. The specific preparation method is as follows: First, the ITO is cleaned in an ultrasonic device with ultrapure water, ethanol, acetone and isopropanol in turn; then, a YG32 film is prepared on the ITO surface as a hole transport layer by spin coating (YG32 is dissolved in chlorobenzene at a concentration of 10 mg / mL), and the spin coating machine parameters are: 3000 r / min, plus The speed is 1000r / 30s; after the hole transport layer is spin-coated, anneal it at 150°C for 30min; after annealing, perform ozone cleaning for 10min; secondly, put the wafer into a glove box, set the humidity to 40%, charge and discharge the air 3 times, and use the anti-solvent spin coating method to prepare the perovskite layer; after completion, each device is annealed at 150°C for 10min and the humidity is 20-30%. After annealing, the wafer turns gray and is returned to the glove box to spin-coat the passivation layer; after spinning the passivation layer, use the evaporation method to deposit the PCBM film and the silver electrode in sequence.

[0036] After the preparation, the performance of the solar cell was tested. The solar cell prepared with nickel oxide as the hole transport layer material was used as the control group.

[0037] The current-voltage (JV) characteristic curve of its battery device performance is shown in Figure 3 and Table 1. Figure 3 As can be seen from Table 1, in the perovskite device, the open circuit voltage V OC is 1.20V, short-circuit current density J SC 22.84 mA / cm 2 The filling factor FF is 86.54%, and the photoelectric conversion efficiency PCE is 23.72%, which improves the device efficiency and device stability.

[0038] Table 1 Device performance

[0039]

Claims

1. An organic phosphonic acid small molecule material, characterized in that: With iminodibenzyl as the central core, n-butyl alkyl chain as the connecting part, and phosphoric acid group as the terminal group, its specific structure is:

2. The method for preparing the organic phosphonic acid small molecule material according to claim 1, characterized in that: The specific steps include: (1) Adding iminodibenzyl, 0.66 g of tetrabutylbromosilane, 1,4-dibromobutane, sodium hydroxide and ultrapure water into a single-mouth bottle; evacuating, filling with nitrogen, and repeating the evacuation and degassing three times; heating to 50-90° C. to react; after the reaction is completed, removing excess tetrabutylbromosilane by extraction; and purifying by silica gel column chromatography to obtain a white solid, which is 5-(4-bromobutyl)-10,11-dihydro-5H-dibenzo[b,f]naphthalenepyridine; (2) Add 5-(4-bromobutyl)-10,11-dihydro-5H-dibenzo[b,f]naphthalene azide and triethyl phosphite into a single-mouth bottle; evacuate, fill with nitrogen, and repeat the evacuation and degassing three times; heat to 120-180° C. for reaction; after the reaction, remove the excess triethyl phosphite by vacuum distillation; and then purify by silica gel column chromatography to obtain a colorless liquid, which is diethyl (4-(10,11-dihydro-5H-dibenzo[b,f]naphthalene azide-5-yl)butyl) phosphate; (3) Diethyl (4-(10,11-dihydro-5H-dibenzo[b,f]azanaphthalen-5-yl)butyl) phosphate, trimethylsilane bromide and 1,4-dioxane are placed in a single-mouth bottle; vacuum is applied, nitrogen is introduced, and the gas is pumped and released three times; methanol is added to quench, and ultrapure water is added for hydrolysis, and the mixture is stirred; finally, a white powder is obtained by filtration, which is (4-(10,11-dihydro-5H-dibenzo[b,f]azanaphthalen-5-yl)butyl) phosphoric acid, i.e., an organic phosphonic acid small molecule material.

3. Use of the organic phosphonic acid small molecule material according to claim 1 as a hole transport layer in a perovskite solar cell device.

4. A perovskite solar cell, characterized in that: The perovskite solar cell comprises a transparent conductive glass, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode which are stacked, and the hole transport layer is the organic phosphonic acid small molecule material according to claim 1.

5. A photovoltaic cell, characterized in that: Comprising the perovskite solar cell as described in claim 4.

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